1. Field of the Invention
The present invention relates to a particle processing apparatus to be used in a wide field including food, medical and chemical industries either for granulating or coating particles on a disk by rotating the disk in a barrel equipped with scrapers or for blending the particles in the barrel by rotating blades in the barrel.
2. Description of the Prior Art
Before entering into the detailed description of the present invention, cursory review will be made on examples of the particle processing apparatus according to prior art with reference to FIGS. 7 and 8. FIG. 7 shows the processing apparatus for the granulating or coating operations, and FIG. 8 shows the processing apparatus for the blending operations. FIGS. 7(a) and 8(a) are top plan sections II--II of FIGS. 7(b) and 8(b), respectively, which are front sections I--I of FIGS. 7(a) and 8(a), respectively, and FIG. 8(c) is a section III--III showing a blade of FIGS. 8(a) and 8(b).
With first reference to FIG. 7, the rotations of an electric motor M are decelerated in conformity with the granulating or coating conditions by a reduction gear mechanism R and are transmitted to a shaft 2. This shaft 2 is borne upright by bearing members 5a and 5b which are supported by a bearing support 5e. A disk 1 has a dish-shaped shallow upper face 1a and is fixed in a horizontal position on the shaft 2. A processing barrel 3 is fixedly placed on a barrel table 3e through its flange 3d and is divided into an upper conical portion 3a, a lower cylindrical barrel 3b and a bottom portion 3c which is formed with an air injection port 4a for compressed air. Between the bottom portion 3c and the lower side of the disk 1, there is defined an air passage which has communication with a small gap 4c left between the outer circumference of the disk 1 and the inner circumference of the barrel portion 3b. A plurality of (e.g., four, as shown) scrapers 6 are provided, each of which is composed of: an arcuate blade 6a, a stem 6b carrying the blade 6a; and a handle 6c for turning the stem 6b. The scrapers 6 are positioned upright in the processing barrel 3. A liquid injection nozzle 7 is provided for injecting a liquid such as a binder onto the particles lying on the upper face 1a of the disk 1 to granulate or coat them.
Now, if the disk 1 is charged on its upper face 1a with a suitable volume of particles and is turned by the motor M, the particles are swirled horizontally, as indicated at P in FIG. 7(a), while being forced from the center of the disk 1 toward the inner circumference of the processing barrel 3 by the centrifugal force of the disk 1. In the course of these swirling motions, the particles are scraped up by the blades 6a of the scrapers 6 so that they are scattered onto the inner circumference of the barrel 3. Simultaneously with this, the particles make slightly small, vertical motions, as indicated at Q in FIG. 7(b), in accordance with the rotations of the disk 1 and the shape of the inner circumference which is defined by the conical portion 3a and the cylindrical trunk portion 3b of the processing barrel 3. As a result, the particles turn back and swirl between the central and circumferential portions of the disk 1.
The granulations and coatings are accomplished by injecting a binder or the like from the liquid injection nozzle 7 onto the particles thus moving. In this instance, the small gap 4c between the disk 1 and the processing barrel 3 is supplied with the compressed air from the injection port 4a by way of the passage 4b so that it can be prevented from getting clogged with the particles.
Turning now to FIG. 8, like FIG. 7, the rotations of an electric motor M' are decelerated by a reduction gear mechanism R' and are transmitted to a shaft 12. This shaft 12 is also borne upright by bearing members 15a and 15b which are supported by a bearing support 15e. Ordinarily two (as shown) or three blades 11 are so mounted on the shaft 12 that they can rotate in a horizontal plane. Each of the blades 11 is formed into such a triangular section as has its leading slope 11a made gentler that the trailing slope 11b, as shown in FIG. 8(c). A processing barrel 13 is fixed on a barrel table 13e through its flange 13d and is composed, like the processing barrel 3 of FIG. 7, of an upper conical portion 13a, a cylindrical trunk portion 13b and a bottom portion 13c (although it is not equipped with the scrapers). The bottom portion 13c is formed at its central portion with an air injection port 14a for compressed air and an air passage 14b, which has communication with a small gap 14c between the shaft 12 and a through hole of the bottom portion 13c.
Now, if a suitable volume of particles are poured into the processing barrel 13 and the blades 11 are likewise rotated, they are caused to make horizontal swirling motions, as indicated at P' in FIG. 8(a), and vertical, small circular motions, as indicated at Q' in FIG. 8(b), by the slopes 11a of the blades 11 and the inner circumference of the processing barrel 13. As a result, the particles make the motions P' as well as the motions Q' so that they are sufficiently blended. In this instance, the small gap 14c of the bottom portion 13c of the blending barrel 13 is supplied with the compressed air from the air injection port 14a by way of the air passage 14b so that it is prevented from getting clogged with the particles.
In the apparatus of the prior art shown in FIGS. 7 and 8, however, high forces are required for turning the disk 1 of FIG. 7 and the blades 11 of FIG. 8 so that the apparatus require high drive powers and are difficult to reduce their sizes.
In order to rotate a body lightly, compressed air has been used in the prior art to make a gas bearing.
On the other hand, the apparatus of FIGS. 7 and 8 according to the prior art have to supply the small gaps 4c and 14c with the compressed air thereby to prevent them from getting clogged with the particles. Generally speaking the particle processing apparatus cannot avoid the clogging with the particles so that the use of the compressed air is unavoidable.